Pilot studies of the effects of chronic d-amphetamine and morphine treatment of pregnant rats and squirrel monkeys are aimed at identifying neuropathology or abnormal developmental patterns in the central nervous system of fetal newborn and postnatal offspring. Selected areas of cerebral cortex and cerebrum (including hippocampus) and brain stem areas (including diencephalon) are under study using combined light and electron microscopy. Similar studies are proceeding in parallel on the effects of chronic drug treatment of adult rats and squirrel monkeys. Light and electron microscopy of experimental and human pathological eyes is directed towards elucidating vascular permeability patterns and the role of abnormal vasculature in such human degenerative diseases as cystoid degeneration and Coats' disease. Experimental material is principally peroxidase-treated monkeys. Retrograde thalamic degeneration in monkeys will be examined electron microscopically, principally in the lateral geniculate nucleus after surgical extirpation of the visual cortex. The principal aim will be to see to what extent the pattern of events is similar to or differs from the response in rabbits. Special attention will be devoted to the problem of distinguishing hematogenous invasion from the response of vessel wall elements and the endogenous macroglial cell population of the thalamus.